A mixture which contains bicarbonate (sodium hydrogen carbonate or potassium hydrogen carbonate) and an organic acid is molded by making tablets or others, thereby providing a bubble-forming composition (solid substance), and this process is applied to products such as a cleaning agent, a bathing agent, a bath-water detergent and a pool-water disinfectant. These products (solid substances) are advantageous in that they will readily dissolve when put into water, while generating carbon dioxide gas in reactions with ingredients thereof, and are also effective in enhancing commercial value as they impart a comfortable feeling from use to consumers. In particular, in a bath liquid (also referred to as a bathing agent), a great emphasis is placed on effects of improvement of blood circulation due to generation of carbon dioxide gas.
On the other hand, very small bubbles, for example, those with a diameter of 0.05 mm or less, which are referred to as micro-bubbles, are widely used in purification treatment of turbid water or discharged water and disinfecting domestic water, etc. For example, where micro-bubbles are generated at a turbid water treatment tank installed in water treatment facilities or others, pollutants suspended in turbid water can be floated and separated by allowing the bubbles to adhere to the pollutants. Where micro-bubbles are generated in closed water areas such as lakes, ponds and culture ponds, they are effective in promoting dissolution of oxygen into water.
Conventionally, as a micro-bubble shower which uses the micro-bubbles, there is known a tap-water pressure based shower which uses a swirl flow (refer to Patent Document 1).
There is also known a combination which is obtained by using a technology which dissolves a carbon dioxide gas-generating ingredient in hot water together with a technology which generates micro-bubbles to disinfect microorganisms in a liquid and purify the liquid (refer to, for example, Patent Document 2).
The technology of Patent Document 1 is such that, as found in various types of bathing agents, a carbon dioxide gas generating article is disposed as a gas generating article inside a gas-liquid mixer and an ejection port side of the gas-liquid mixer is connected to a shower head, and hot water obtained by mixing a bathing ingredient with micro-bubbles is ejected from the shower head, by which cleaning effects and health promoting effects such as improvement of blood circulation can be expected to be obtained.
On the other hand, there is also known a technology in which a carbon dioxide gas bath tablet is accommodated in the vicinity of the ejection port inside the shower head (refer to Patent Documents 3 to 5).